1. Field of the Invention
This invention relates to the recovery of cobalt containing residues and/or wastes especially residues or wastes of the chemical industry which contain cobalt or colbalt compounds often in the presence of great excesses of accompanying substances such as organic or inorganic chemicals. The process of the present invention comprise heating the cobalt containing residue in the present of air to convert the cobalt to cobalt oxide.
2. Discussion of the Prior Art
In numerous processes of the chemical industry, residues containing cobalt are produced. Since cobalt and its compounds are used especially as catalysts, these residues are so greatly contaminated with organic or inorganic substances, and frequently with both, that the valuable cobalt has hitherto not been recoverable.
Such residues are formed especially in reactions in which cobalt-containing catalysts are used, in the form of either cobalt metal or cobalt compounds which are unsupported or supported on carbon or carbon compounds. Examples are Raney cobalt and organic cobalt compounds in which the cobalt is bound in homeopolar or in complex form to carbonyl, nitrosyl, cyano or olefin groups, for example, or in some cases also to phosphine residues, and which in some cases may also contain alkali or alkaline earth ions. Such reactions are very numerous, examples being hydrogenation and dehydrogenation, oxo synthesis, the numerous variants of the Reppe synthesis, and the syntheses which are performed with the use of cobalt carbonyl compounds, to mention but a few.
Such wastes and residues produced in chemical processes have in many cases low contents of cobalt ranging from 0.01 to 10%, especially from 0.05 to 5%, by weight, often in addition to high contents or organic substances and frequently high contents of soluble salts, especially alkali metal salts such as sodium chloride or potassium chloride. Used cobalt catalysts are also encountered which have high cobalt contents, e.g. up to 90 or 95 wt.% Co, reconed as metal. Furthermore, these wastes or residues often are in moist form or dissolved or suspended in water or other liquids. The processes commonly known in metallurgy are impractical in these cases on account of the large amount of accompanying substances. The conversion of the cobalt to metallic cobalt, by reduction for example, is too expensive.